An electric machine, in particular a synchronous machine for a hybrid or electric vehicle, usually comprises a stator unit and a rotor unit, which can be rotated in relation to the stator unit, as well as a housing for receiving the stator unit and the rotor unit. Such an electric machine may be used for driving a vehicle and during operation can produce a nominal power of, for example, up to 35 kW and a peak power of, for example, up to 70 kW.
Due to the design and operating mode of an electric machine, during operation eddy currents are produced in the rotor unit of the electric machine and therefore an induction voltage builds up during operation of the electric machine until it abruptly dissipates in the form of an electric discharge via a mounting of the rotor unit or a shaft toothed structure of a rotor shaft of the electric machine. In so doing, such an electric discharge can cause electro erosive wear on working bodies of the mounting or on tooth flanks of the shaft toothed structure or so-called zebra stripe patterns on the working bodies or the tooth flanks and consequently damage the mounting or the shaft toothed structure.